CD73-Adenosinergic Axis Mediates the Protective Effect of Extracellular Vesicles Derived from Mesenchymal Stromal Cells on Ischemic Renal Damage in a Rat Model of Donation after Circulatory Death.

We propose a new organ-conditioning strategy based on mesenchymal stromal cell (MSCs)/extracellular vesicle (EVs) delivery during hypothermic perfusion. MSCs/EVs marker CD73 is present on renal proximal tubular cells, and it protects against renal ischemia-reperfusion injury by converting adenosine monophosphate into adenosine (ADO). In this study, after checking if CD73-silenced EVs (EVsi) would impact in vitro tubular-cell proliferation, we perfused kidneys of a rat model of donation after circulatory death, with Belzer solution (BS) alone, BS supplemented with MSCs, EVs, or EVsi. The ADO and ATP levels were measured in the effluents and tissues. Global renal ischemic damage score (GRS), and tubular cell proliferation index (IPT) were evaluated in the tissue. EVsi did not induce cell proliferation in vitro. Ex vivo kidneys perfused with BS or BS + EVsi showed the worst GRS and higher effluent ADO levels than the MSC- and EV-perfused kidneys. In the EV-perfused kidneys, the tissue and effluent ATP levels and IPT were the highest, but not if CD73 was silenced. Tissue ATP content was positively correlated with tissue ADO content and negatively correlated with effluent ADO level in all groups. In conclusion, kidney conditioning with EVs protects against ischemic damage by activating the CD73/ADO system.

Trained breathing-induced oxygenation acutely reverses cardiovascular autonomic dysfunction in patients with type 2 diabetes and renal disease.

AIMS: Cardiovascular autonomic dysfunction, evaluated as baroreflex sensitivity (BRS), could be acutely corrected by slow breathing or oxygen administration in patients with type 1 diabetes, thus suggesting a functional component of the disorder. We tested this hypothesis in patients with the type 2 diabetes with or without renal impairment. METHODS: Twenty-six patients with type 2 diabetes (aged 61.0 ± 0.8 years, mean ± SEM; duration of diabetes 10.5 ± 2 years, BMI 29.9 ± 0.7 kg/m(2), GFR 68.1 ± 5.6 ml/min) and 24 healthy controls (aged 58.5 ± 1.0 years) were studied. BRS was obtained from recordings of RR interval and systolic blood pressure fluctuations during spontaneous and during slow, deep (6 breaths/min) controlled breathing in conditions of normoxia or hyperoxia (5 l/min oxygen). RESULTS: During spontaneous breathing, diabetic patients had lower RR interval and lower BRS compared with the control subjects (7.1 ± 1.2 vs. 12.6 ± 2.0 ms/mmHg, p < 0.025). Deep breathing and oxygen administration significantly increased arterial saturation, reduced RR interval and increased BRS in both groups (to 9.6 ± 1.8 and 15.4 ± 2.4 ms/mmHg, respectively, p < 0.05, hyperoxia vs. normoxia). Twelve diabetic patients affected by chronic diabetic kidney disease (DKD) presented a significant improvement in the BRS during slow breathing and hyperoxia (p < 0.025 vs. spontaneous breathing during normoxia). CONCLUSIONS: Autonomic dysfunction present in patients with type 2 diabetes can be partially reversed by slow breathing, suggesting a functional role of hypoxia, also in patients with DKD. Interventions known to relieve tissue hypoxia and improve autonomic function, like physical activity, may be useful in the prevention and management of complications in patients with diabetes.